who was orsino?

Orsino, Duke or Count of Illyria

Though his title in the play is disputed, Orsino is the ruler of Illyria, with some naval experience behind him. He is lovesick for the Lady Olivia, who will not return his affections; Viola is taken into his service, as the boy Cesario, and is quickly taken into his confidence and tries to woo Olivia for him. However, Orsino's affections shift by the end of the play; he drops his self-indulgent behavior, and develops affection for Viola.